They really should just do a Kids season and have it be for vocalists under 16 or 18. Then they should raise the age limit for the regular seasons and let everyone else compete.
As much as I think that Kennedy, We, Danielle Bradbury, Sawyer, Jacquie Lee, et al had great voices, I also think they weren't ready. Having a good voice isn't all it takes, and in all of these cases the singers lacked emotional maturity, depth, technique, and consistency. Look at Brynn from last season - in the span of a single song she'd go from pitchy and awful to sounding really good. And her performances we